Extreme pressure lubricant containing asbestos fibers



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3,0i,8% Patented Nov. 28, 195i 3,010,896 EXTREME PRESSURE LUBRICANT CONTAINING ASBESTOS ERS Norman R. ()dell, Fishkili, and Joseph F. Lyons, Poughlreepsie, N.Y., assignors to Texaco Inc., New York, N.Y., a corporation of Delaware No Drawing. Filed Aug. 26, 1059, Scr. No. 836,060 11 Claims. (Cl. 252-133) This invention relates to improved lubricating compositions containing asbestos fibers.

Asbestos fibers have been employed heretofore in lubricating compositions as a filler to obtain improved load bearing properties. The asbestos fibers which have been employed for this purpose have only a low thickening effect in lubricating oils and tend to settle out upon standing, about 15 percent by weight or more being required in order to obtain a stable composition. They also have the disadvantage of causing greatly increased wear of the lubricated metal parts. For this reason, asbestos filled lubricants have been considered suitable only for rough uses such as the lubrication of crawler type tractors.

We have now found that lubricating compositions are obtained having high load bearing properties equivalent to those of asbestos filled lubricating compositions of the prior art but without the disadvantage of causing excessive wear of lubricated metal parts by employing in the composition relatively small amounts of ultra fine asbestos fibers, having cross-sectional diameters of colloidal size. These fibers have a high thickening effect in lubricating oils, differently from the asbestos fibers employed heretofore, and form stable systems of substantially improved load bearing properties even in very low concentrations. The asbestos fibers having these .properties in lubricating oils have cross-sectional diameters below about 0.1 micron and fiber lengths below about 3000 microns, suitably in about the range 50-3000 microns. Particles in this size range are obtainable from asbestos rock by mechanical purification and separation methods and by chemical methods, such as that described In US. 2,626,213, which involves disintegrating the asbestos rock by means of aqueous solutions of surface active compounds which are adsorbed by the asbestos fibers.

This invention contemplates lubricating compositions comprisinga major amount of a lubricating oil and a minor amount, sufficient to impart substantially improved load bearing properties to the composition, of asbestos fibers of the character, described above. Ordinarily the suitably about l-8 percent by weight of the composition. They may be employed very advantageously in grease forming amounts, such as above about 4 percent by I They are also very advantageously employed in greases in combination with other thickening agents such as the conventional metal fatty acid soaps or finely divided solids of the types employed as thickening agents or fillers in greases, such as carbon black, silica gel, clays, organic pigments and metal oxides. By the combination of the asbestos fibers with other thickening agents of these types, compositions of improved load bearing properties are obtained in combination with other a specially desired properties and the characteristic fibrous texture obtained with the asbestos alone may be modified,

where this is considered objectionable.

The lubricating oils forming the major constituent of these compositions may be any oils of lubricating characteristlcs which are suitable for use in lubricating compositions generally. Such oils include the conventional mineral lubricating oils having Saybolt Universal visof compounds. alsoincludes 2-ethylhexyl azelate, di-iso-octyl adipate, etc.

cosities in the range from about seconds at F. toabout 225 seconds at 210 R, which may be either naphthenic or parafiinic in'type or blends of different oils. The preferred lubricating oils are those having Saybolt Universal viscosities in the range from about 300 seconds at 100 F. to about 100 seconds at 210 R, which may be blends of lighter and heavier oils in the lubricating oil viscosity range. Synthetic lubricating oils, which may be preferred for obtaining greases having special properties required for certain types of lubricating service, including oils prepared by cracking and polymerizing products of the Fischer-Tropsch process and the like as Well as other synthetic oleaginous compounds such as polyethers, polyesters, silicone oils etc., having viscosities within the. lubricating oil viscosity range. Suitable polyethers include particularly polyalkylene glycols such as polyethylene glycol. Suitable polyesters include the aliphatic dicarboxylic acid diesters, such as di-Z-ethylhexyl sebacate, di(secondary amyl)sebacate, di- The sulfur analogs of the polyalkylene ethers and polyesters are also suitable.

A particularly suitable class of dicarboxylic acid ester oils are those disclosed by R. T. Sanderson in US. 2,628,974, obtained by reacting dibasic aliphatic acids With glycols and end blocking the reaction products With monohydric aliphatic alcohols or monocarboxylic aliphatic acids. The preferred materials of this character are products obtained by reacting a monoor polyalkylene glycol with a dicarboxylic acid and a monohydric alcohol, represented by the formula wherein R is an aliphatic group or an aliphatic ether group containing from 4 to 12 carbon atoms, R is an aliphatic group containing from 1 to 12 carbon atoms, and x is an integer from 1 to 5.

The silicone oils are compounds having the general wherein R represents alkyl, aryl, alkaryl or aralkyl groups, which may be the same or different, and n is a number vsufiicient to give a viscosity in the lubricating oil range to the compound, preferably aviscosity in about the range from 70 to 900 seconds Saybolt Universal at 100 F. Suitable compounds of this type include dimethyl silicone polymer, diethyl silicone polymer, methylcyclohexylsilicone polymer, diphenyl silicone polymer, methylethyl silicone polymer, methyltolyl silicone polymer, etc; These materials may be prepared by various methods, including the hydrolysis of hydrolyzable organic-substituted silanes, as described, for example, in US. 2,410,346 and US. 2,469,888. This class halogenated compounds, particularly chlorinated compounds, wherein the halogen atoms are preferably attached to aryl groups represented by R. Particularly suitable compounds are methylchlorophenyl s licones having a chlorine content of at least ,formula 35 percent by weight of the groups represented by R 7 the trade name of Versilube F50.

Additives of the usual types employed in lubricating compositions may also be present, such as oxidation inhibitors, corrosion inhibitors, tackiness agents, such as various high polymer materials, extreme pressure agents, etc. Suitable oxidation inhibitors include particularly those of the amine type, such as phenylalphanaphthylgrams of mixture thereafter allowed to 'tained as described above amine, diphenylparaphenylenediamine, tetramethyldiaminodiphenyl methane and bis(2-hydroxy-3-t-butyl-5-methylphenyl) methane. With particular advantage, a'surface active agent of the type which imparts Water resistant properties to inorganic solids may be employed, such as quaternary ammonium salts of fatty acids, polyglycol ethers, metal alkyl sulfates or sultonates, etc.

The grease preparation may be carried out by merely EXAMPLE I A lubricating grease having the following composition in percent by weight:

Asbestos fibers 4.7 Diphenylparaphenylenediamine 1.0 Lubricating nil .943.

The lubricating oil is a synthetic ester obtained by reacting together sebacic acid, Z-ethylhexane-l, B-diol and Z-ethylhexanol in about a 2:1:2 ratio, respectively, and consists predominantly of the compound The asbestos fibers are obtained from a commercial asbestos paper, prepared as disclosed in US. 2,626,213,

by treating crysotile asbestos with an aqueous solution of dioctyl sodium sulfosu ccinate, filtering off impurities and drying the dispersed asbestos fibers containing about 8-l0 percent by weight of adsorbed surfactant in the 7 form of sheets. The sheets comprise asbestos fibers having cross-sectional diameters below 0.1 micron,

with the major portion in the 0.02-0.05 micron range, and afiber length in about the range 100-3000 microns.

The asbestos fibers employed in the grease preparation are obtained from this material by refluxing pieces of the asbestos sheets with methylethylketone for eight hours .methylethylketone.

The method of grease preparation is as follows: 300 7 the wet asbestos pulp (containing 58.6 grams of-the asbestos fibers on a dry weight basis) are mined with600 grams of the synthetic ester. oil and the mixture heated at 300-320 F. for three hours in order'to remove methylethylketone contained in the pulp,

cool.

andthe An additional 600' grams of the synthetic ester oil and 11.7 grams of diphenylparaphenylenediamine are added with stirring when the temperature of. the mixture is about 200 F.

A brown, fibrous, N.L.G.I. N0. 1 grade grease is obhaving an;ASTM penetration at 77'F.of ,302 both unworked and worked,.60 strokes, and anASTM dropping point above 500 F. Itcarries a load of 69 kg. in the mean Hertz load test, and gives ,a'sc ar diameter of 0356mm. 1n thefour ball wear test -(5 log. 1oad; 1800'1-. .m.,- 130: F.). These tests are indicative of very superior load bearing properties compared with other greases,-including other solids thickened greases, not containinglextreme pressure additives,

and also show that this grease gives very-low weargs compared with other solids thickened greases. J

. obtained as described above.

4 EXAMPLE n Asbestos fibers 5.0 Lubricating oil 95.0

The lubricating oil is Versiiube FS0. Typical tests upon this product show a Saybolt Universal viscosity at F. of 253, a molecular weight of 2760, a silicone content of 33.6 percent and a chlorine content of 7.18 percent.

The asbestos ample I.

The grease preparation is carried out by heating together 58.6 grams of the asbestos fibers in the form of the methylethylketone wet pulp and 600 grams of silicone oil at 300-320 F. for three hours to remove the methyl ethylketone, and then stirring in an additional 520 grams of the silicone oil when the mixture has cooled to about 200 F.

A tan, fibrous, N.L.G.I. No. 2 grade grease is obtained as described above, having load bearing and antiwear properties substantially equivalent to those of the grease described in Example I, and having good water stability in addition to other desirable lubricating properties. It has an ASTM penetration at 77 F. of 302 unworked, 290 worked 60 strokes, 324 worked 100,000 strokes, and an ASTM dropping point above 500 F. The Water resistance properties of this grease are shown by the following tests:

fibers employed are as described in Ex- Dynamic water resistance test, loss, percent 7.5; 10 Water absorption, percent 20 Worked penetration before test 290 Worked penetration after test 287 EXAMPLE III A lubricating grease having the following composition The asbestos fibers employed are obtained by merely disintegrating the commercial asbestos paper describe in Example I by pumping it with water in a Waring Blender for5' minutes and filtering.

The lubricating oil is a refined naphthenic distillate oil having a Saybolt Universal viscosity at 100 F. of 317 seconds.

The grease is prepared by mixing 6.8 pounds of the wet asbestos pulp (containing 400 grams of asbestos on a dry weight basis) with 1300 grams of the lubricating oil, heating at 3l0e320 F. for two hours with stirring to dehydrate, and adding an'additional 4045 grams of the oil during cooling. 7

A soft, brown, fibrous, N.L.G.I. No. 1 grade grease is It has an ASTM penetra= tion at 77 F. of 332 unworked, 317 worked 60 strokes,

and 381 worked 100,000 strokes, and an ASTM dropping point above 500 F. The following table shows the load bearing properties of this grease in comparison with those of other greases'co'ntaining difierent thickening agents in the same lubricating oil base.

V V Tablel r Thickener: Mean Hertz load, kg. Na stearate, 25% 20 Silica (organo-treated), 30% 23 Carbon black, 13% 2 Asbestos fibers, 6.4%."; 39

' In addition to the superior load bearing properties as erties for a solids thickened grease, as shown by a scar diameter of 0.419 mmiinthe tour ball wear test. This compares, for example with'0 52l mm. obtained with a silica thickened grease comprising a base oil of the same type.

Obviously many modifications and variations of the vention as hereinbefore set forth may be made without departing from the spirit and scope thereof and only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A lubricating composition consisting essentially of a lubricating oil as the predominant constituent and about 05-120 percent by weight, sufiicient to impart substantially improved load bearing properties to the composition, of asbestos fibers having a cross-sectional diameter below about 0.1 micron, with the major portion in about the range 0.02-0.05 micron, and a fiber length in about the range 50-3000 microns.

2. A lubricating composition according to claim 1 wherein the said lubricating oil is an aliphatic polyester.

3. A lubricating composition according to claim 1 wherein the said lubricating oil is a silicone oil.

4. The lubricating composition according to claim 1 wherein the said asbestos fibers are present in a grease forming proportion.

5. A lubricating composition according to claim 1 wherein the said asbestos fibers are coated with a surface active compound chosen from the class of sulfonates.

6. A lubricating composition consisting essentially of a lubricating oil as the predominant constituent thickened to a grease consistency with about 4-8 percent by weight of asbestos fibers having a cross-sectional diameter below about 0.1 micron, with the major portion in about the range 0.02-0.05 micron, and a fiber length in about the range -3000 microns.

7. A lubricating composition according to claim 6 wherein the said lubricating oil is an aliphatic polyester.

8. A lubricating composition according to claim 6 wherein the said lubricating oil is a silicone oil.

9. A lubricating composition according to claim 6 wherein the said lubricating oil is a methylchlorophenyl silicone oil.

10. A lubricating composition according to claim. 6 wherein the said asbestos fibers are coated with a surface active compound chosen from the class of sulfonates.

11. A lubricating composition according to claim 6 wherein the said asbestos fibers are coated with a diester of sodium sulfosuccinate.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Klemgard, Reinhold Publ.

and 689.

Lubricating Greases, C0rp., N.Y., 1937, pages 686 

1. A LUBRICATING COMPOSITION CONSISTING ESSENTIALLY OF A LUBRICATING OIL AS THE PREDOMINANT CONSTITUENT AND ABOUT 0.5-12.0 PERCENT BY WEIGHT, SUFFICIENT TO IMPART SUBSTANTIALLY IMPROVED LOAD BEARING PROPERTIES TO THE COMPOSITION, OF ASBESTOS FIBERS HAVING A CROSS-SECTIONAL DIAMETER BELOW ABOUT 0.1 MICRON, WITH THE MAJOR PORTION IN ABOUT THE RANGE 0.02-0.05 MICRON, AND A FIBER LENGTH IN ABOUT THE RANGE 50-3000 MICRONS. 